Alpha-tACS effect on inhibitory control and feasibility of administration in community outpatient substance use treatment.

Background: Deficits in inhibitory control (IC) and distress tolerance (DT) are associated with substance use disorders (SUD) and post-treatment return to substance use. Transcranial alternating current stimulation (tACS) modulates the neural oscillations that are associated with the cognitive and affective mechanisms contributing to IC and DT. The aims of the current study were to examine the feasibility and acceptability of administering tACS in a community-based SUD treatment setting, and to test the effect of alpha-tACS on IC and DT.

Method: A double-blind, randomized, active sham-controlled trial of treatment-seeking adults with a SUD (N = 30, Mean = 43.2 years, 70.0% male). Participants attended two sessions and completed computerized inhibitory control and distress tolerance tasks while receiving tACS targeting the bilateral dorsolateral prefrontal cortex (DLPFC). Participants received sham-tACS and were then randomized to receive sham-, alpha-, or gamma-tACS within 2-3 days.

Results: Treatment retention was 87%. Participant self-reported belief of having received tACS and mean side effect intensity ratings did not differ across conditions, with all side effect ratings in the absent to mild range. There was a large (d = 0.83) and significant effect of alpha-tACS on inhibitory control compared to sham-tACS (β = 1.78, SE = 0.65, 95 % CI: 0.41, 3.14, p<0.01). There were no significant effects of condition on distress tolerance.

Conclusions: To our knowledge, this is the first study of tACS in adults with a SUD. Our findings provide preliminary evidence for recruitment, retention, and administration feasibility of tACS in a community-based substance use treatment program and a beneficial effect of alpha-tACS on inhibitory control.